1. Field of the Invention
The present invention relates to a tool assembly for a punch press having at least one laser welding apparatus. The laser welding apparatus includes a focusing device and at least one supporting block for a guided supporting of said focusing device of the laser welding apparatus. The focusing device features a predetermined focal length and a predetermined focal point. The tool assembly includes further a body having a working surface with at least one recess for a die to be inserted thereinto. The die has a cutting edge which is aligned with a surface portion of the working surface of said body. The supporting block is designed and arranged in such a manner that a laser beam emitted by the focusing device mounted to the supporting block is focused to a predetermined point at the die corresponding to the focal point of the focusing device such to perform a welding operation at a workpiece located thereat. The supporting block includes at least one guiding surface for positioning the supporting block relative to the focal point at the die.
2. Description of the Prior Art
Punch presses, of which the operation encompasses additionally to a mechanical punching of workpieces also a welding thereof by means of a laser welding apparatus, are utilized, for instance, for the production of stacks of plates or metal sheets used in electrotechnical products. Examples of such products are packages of plates used for laminated yokes of an electrical device or also for stators and rotors of electromotors. The individual plates or metal sheets are individually punched and stacked, whereby the stacking is, for instance, achieved, in that a braking member is located in or below a die cooperating with a punch. When stacking the consecutively punched plates, each plate set onto the stack is welded at at least one location to the previously stacked plate located thereunder, for instance, by means of a laser beam, whereby the beaming of the laser beam proceeds commensurate with the operating cycle of the punch press. The laser welding of the stamped plates to the stack located in the die proceeds until a predetermined number of individual plates has been welded together to form a stack of plates. Thereafter no welding is performed during a next following punching stroke of the punch press, such that finally the welded stack of plates is urged out and away from the braking member by the next following stack of plates punched into the die.
The die, also called female die or bottom die, is generally a sleevelike product made of a hard metal, which is set into a corresponding opening in the lower tool of the punch press and located specifically in such a manner that the cutting edge of the die is aligned with the operating surface of the lower tool.
As is generally known, the cutting edges of the dies are subject to wear during prolonged operation and it is generally known that the tools, i.e. specifically their working surfaces, are periodically ground in order to obtain again the original sharpness of the cutting edge(s).
The sheets or plates which are stamped are extremely thin and due to this reason and also due to reasons of welding techniques it is necessary to set the respective welding points of the laser beam welding with tolerances of a few 1/100 mm. This demand causes obviously a correspondingly precisely located mounting of the optical part, the focusing device of the laser welding apparatus, of which the focal depth or distance and the focal point determine the respective welding point. The focusing devices of laser welding apparatuses are commonly mounted to a part of the frame or also to a tool of the punch press and are initially set when setting up the punch press such as all the cutting, grooving, etc. tools thereof with a high precision.
If now the tool is dismounted and removed in order to newly grind the working surface due to the reason mentioned above, all focusing devices mounted thereonto must be adjusted newly after assembling the tool in the punch press because due to mentioned grinding the location of the welding points are now shifted relative to the earlier, initial focal point of the focusing device. This new adjusting and setting up of the focusing devices is a tedious, time consuming process.